Check out this IG post from @entrepreneursquote, listing 5 free course from MIT.
You can actually go to https://ocw.mit.edu/, to checkout all the courses that they offer and most are free that you can download but will not give you a certificate even if you complete the course.
- Cryptocurrency Engineering and Design
- Introduction to Computer Science and Programming
- Software Construction
- Intro to Computer Science with Python
- Introduction to Computational Thinking and Data Science